Vehicle roof structure

ABSTRACT

The present disclosure provides a vehicle roof structure including: a left and right pair of roof side rails configuring part of a roof section of a vehicle body, the roof side rails are supported by a center pillar configuring part of the vehicle body and extend along a vehicle front-rear direction; a roof reinforcement portion formed of fiber reinforced plastic, the roof reinforcement portion disposed between the roof side rails so as to extend along a vehicle width direction; and a coupling section formed of metal, the coupling section couples the roof side rails and the roof reinforcement portion, and includes a weak section, the weak section deforms under a collision load in the vehicle width direction prior to the roof reinforcement portion undergoing bending deformation under the collision load.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 from Japanese PatentApplication No. 2016-199436, filed on Oct. 7, 2016, the disclosure ofwhich is incorporated by reference herein.

BACKGROUND Technical Field

The present disclosure relates to a vehicle roof structure.

Related Art

Japanese Patent Application Laid-Open (JP-A) No. 2014-091462 discloses avehicle body structure of an automobile. In this automobile vehicle bodystructure, a left and right pair of roof side rails that configure partof a roof section of a vehicle body are coupled to a roof arch (areinforcement portion) extending along a vehicle width direction. Upperend portions of vehicle body center pillars are also coupled together bythe roof arch. Thus, in JP-A 2014-091462, collision load at the time ofa collision from the side (hereafter, referred to as “side collision”)of the vehicle can be sustained by the roof arch. Moreover, since theroof arch is configured from carbon fiber reinforced plastic (referredto as CFRP below), the weight of the vehicle body may also be reduced.

However, in the above case, in a case in which collision load in sidecollision of the vehicle were to be transmitted to the roof arch withoutbeing absorbed by portions other than the roof arch, it is conceivablethat the roof arch would break at an initial stage of the sidecollision, thus making sufficient absorption of the collision loaddifficult. Namely, in the above case, there is room for improvement fromthe perspective of achieving both weight reduction of the vehicle bodyand securing the absorption efficiency of collision load in a sidecollision of the vehicle.

SUMMARY

The present disclosure provides a vehicle roof structure that may reducethe weight of a vehicle body and may secure the absorption efficiency ofcollision load in a side collision of a vehicle.

A first aspect of the present disclosure is a vehicle roof structureincluding: a left and right pair of roof side rails configuring part ofa roof section of a vehicle body, the roof side rails are supported by acenter pillar configuring part of the vehicle body and extend along avehicle front-rear direction; a roof reinforcement portion formed offiber reinforced plastic, the roof reinforcement portion disposedbetween the roof side rails so as to extend along a vehicle widthdirection; and a coupling section formed of metal, the coupling sectioncouples the roof side rails and the roof reinforcement portion, andincludes a weak section, the weak section deforms under a collision loadin the vehicle width direction prior to the roof reinforcement portionundergoing bending deformation under the collision load.

According to the first aspect of the present disclosure, the left andright pair of roof side rails configuring part of the roof section of avehicle body and extending along the vehicle front-rear direction aresupported by a center pillar configuring part of the vehicle body. Theroof reinforcement portion extending along the vehicle width directionis disposed between the roof side rails. In a side collision of thevehicle, a collision load transmitted through the center pillar and theroof side rails may be sustained by the roof reinforcement portion. Theroof reinforcement portion is also formed of fiber reinforced plastic,enabling a weight reduction in the roof section, and hence in thevehicle body, to be achieved.

However, since the roof reinforcement portion described above is formedof fiber reinforced plastic, in a case in which a collision load in aside collision of the vehicle were to be transmitted to the roofreinforcement portion without being absorbed by portions other than theroof reinforcement portion, the roof reinforcement portion may break atan initial stage of the side collision.

In the present disclosure, the coupling section formed of metal isincluded, and the roof side rails and the roof reinforcement portion arecoupled together by the coupling section. The coupling section is alsoprovided with the weak section. The weak section deforms under acollision load in the vehicle width direction prior to the roofreinforcement portion undergoing bending deformation under the collisionload. Note that herein, bending deformation also includes bucklingdeformation. Accordingly, collision load in a side collision of thevehicle is absorbed by the weak section at an initial stage of the sidecollision, after which the collision load is transmitted to the roofreinforcement portion and absorbed by the roof reinforcement portion.

In a second aspect of the present disclosure, in the above first aspect,the weak section may be formed with a protruding bead portion, theprotruding bead portion may extend along the vehicle front-reardirection and may protrude toward a neutral axis side of vehiclevertical direction bending in the coupling section due to the collisionload.

According to the second aspect of the present disclosure, the protrudingbead portion that extends along the vehicle front-rear direction isformed at the weak section provided to the coupling section. Theprotruding bead protrudes toward the neutral axis side of vehiclevertical direction bending in the coupling section due to a collisionload in the vehicle width direction. Accordingly, at the location wherethe protruding bead portion is provided to the weak section, the secondmoment of area of the cross-section of the weak section with respect tothe neutral axis is smaller than at other locations of the weak section,enabling the protruding bead portion to be the origin of deformation.

In a third aspect of the present disclosure, in the above second aspect,the weak section may include, the protruding bead portion formed furthertoward a vehicle width direction outer side than an inner sideconnection portion that connects the coupling section and the roofreinforcement portion, and an indented bead portion indented to anopposite side to the neutral axis and extending along the vehiclefront-rear direction, the indented bead portion is formed further towarda vehicle width direction inner side than an outer side connectionportion that connects the coupling section and the roof side rails andfurther toward the vehicle width direction outer side than theprotruding bead portion; and the outer side connection portion may beprovided at a portion to a vehicle lower side of the roof side rails,and the protruding bead portion and the indented bead portion may bedisposed further toward a vehicle upper side than the outer sideconnection portion and further toward the vehicle lower side than anapex of the roof side rails.

According to the third aspect of the present disclosure, the protrudingbead portion is formed at the weak section. The protruding bead portionis positioned further toward the vehicle width direction outer side thanthe inner side connection portion connecting the coupling section andthe roof reinforcement portion. The indented bead portion that isindented to the opposite side to the neutral axis and that extends alongthe vehicle front-rear direction is also formed at the weak section. Theindented bead portion is positioned further toward the vehicle widthdirection inner side than the outer side connection portion connectingthe coupling section and the roof side rails.

Thus, in a case in which the coupling section receives a collision loadin the vehicle width direction, the portion of the weak section aroundthe protruding bead portion deforms so as to form a protrusion on theneutral axis side, with the protruding bead portion acting as the originof deformation. In contrast thereto, the location of the weak sectionwhere the indented bead portion is provided is less liable to undergobending deformation, since the second moment of area of thecross-section of the weak section with respect to the neutral axis isgreater than at other locations of the weak section. As a result, as thedeformation process of the weak section progresses, the portion betweenthe protruding bead portion and the indented bead portion deforms so asto pivot about the indented bead portion toward the vehicle verticaldirection.

Moreover, the outer side connection portion is provided at the portionto the vehicle lower side of the roof side rails, and the protrudingbead portion and the indented bead portion are disposed further towardthe vehicle upper side than the outer side connection portion andfurther toward the vehicle lower side than the apex of the roof siderails. Accordingly, the portion of the weak section between theprotruding bead portion and the indented bead portion deforms so as topivot toward the vehicle upper side. After the weak section hasdeformed, the collision load is transmitted from the roof side rails tothe roof reinforcement portion through the portion of the couplingsection further toward the vehicle width direction inner side than theprotruding bead portion. As a result, the load placed on the outer sideconnection portion due to the collision load F may be suppressed.

In a fourth aspect of the present disclosure, in the above secondaspect, the weak section may include, a first indented bead portionindented toward an opposite side to the neutral axis and extending alongthe vehicle front-rear direction, the first indented bead portion formedfurther toward a vehicle width direction outer side than an inner sideconnection portion that connects the coupling section and the roofreinforcement portion, a second indented bead portion indented to theopposite side to the neutral axis and extending along the vehiclefront-rear direction, the second indented bead portion formed furthertoward a vehicle width direction inner side than an outer sideconnection portion that connects the coupling section and the roof siderails, and the protruding bead portion formed between the first indentedbead portion and the second indented bead portion; and the outer sideconnection portion may be provided at a portion at a vehicle lower sideof the roof side rails, and the protruding bead portion, the firstindented bead portion, and the second indented bead portion may bedisposed further toward a vehicle upper side than the outer sideconnection portion and further toward the vehicle lower side than anapex of the roof side rails.

According to the fourth aspect, the first indented bead portion, thesecond indented bead portion, and the protruding bead portion are formedat the weak section. The first indented bead portion is positionedfurther to the vehicle width direction outer side than the inner sideconnection portion connecting the coupling section and the roofreinforcement portion. The first indented bead portion is indented tothe opposite side to the neutral axis and extends along the vehiclefront-rear direction. The second indented bead portion is configuredsimilarly to the first indented bead portion, and is positioned furthertoward the vehicle width direction inner side than the outer sideconnection portion connecting the coupling section and the roof siderails. The protruding bead portion is formed between the first indentedbead portion and the second indented bead portion.

Thus, in a case in which the coupling section receives a collision loadin the vehicle width direction, the portion of the weak section aroundthe protruding bead portion deforms so as to form a protrusion on theneutral axis side, with the protruding bead portion acting as the originof deformation. In contrast thereto, the locations of the weak sectionwhere the first indented bead portion and the second indented beadportion are provided are less liable to undergo bending deformation,since at these locations, the second moment of area of the cross-sectionof the weak section with respect to the neutral axis is greater than atother locations of the weak section. Moreover, the outer side connectionportion is provided to the portion at the vehicle lower side of the roofside rails, and the protruding bead portion, the first indented beadportion, and the second indented bead portion are disposed furthertoward the vehicle upper side than the outer side connection portion andfurther toward the vehicle lower side than the apex of the roof siderails. Thus, as the deformation process of the weak section progresses,the portion between the first indented bead portion and the secondindented bead portion deforms so as to protrude and kink toward thevehicle upper side.

In a fifth aspect of the present disclosure, in the above first aspect,the weak section may be provided between an inner side connectionportion, configuring a part of the coupling section and is connected tothe roof reinforcement portion, and an outer side connection portion,configuring a part of the coupling section and is connected to the roofside rails, and the weak section may be configured by a thinned portionformed thinner than the inner side connection portion and the outer sideconnection portion.

According to the fifth aspect, the weak section is disposed between theinner side connection portion configuring part of the coupling sectionand connected to the roof reinforcement portion and the outer sideconnection portion configuring part of the coupling section andconnected to the roof side rails. The weak section is configured by athinned portion that is formed thinner than the inner side connectionportion and the outer side connection portion. Thus, in a case in whicha collision load in the vehicle width direction is input, the thinnedportion undergoes bending deformation, thereby absorbing the collisionload. Accordingly, the fifth aspect may simplify the configuration ofthe weak section, compared to cases in which a bead portion or the likeis provided to the coupling section so as to set the weak section.

A sixth aspect of the present disclosure, in the above aspects, mayfurther include a high rigidity portion provided to the coupling sectionand between the roof reinforcement portion and the weak section, thehigh rigidity portion may be set with a higher rigidity with respect tobending in a vehicle vertical direction than a rigidity of the roofreinforcement portion.

According to the sixth aspect, the high rigidity portion is providedbetween the roof reinforcement portion and the weak section in thecoupling section. The high rigidity portion is set with a higherrigidity with respect to bending in the vehicle vertical direction thanthe rigidity of the roof reinforcement portion. Thus, the sixth aspectmay increase the certainty that the weak section will deform before theroof reinforcement portion due to the bending moment resulting from acollision load in the vehicle width direction.

As explained above, the vehicle roof structure according to the firstaspect may reduce the weight of the vehicle body and may secure theabsorption efficiency of collision load in a side collision of thevehicle.

The vehicle roof structure according to the second aspect may set, at afreely selected position, the origin of deformation for a case in whichthe coupling section that couples the roof reinforcement portion and theroof side rails together deforms under a collision load in a sidecollision of the vehicle.

The vehicle roof structure according to the third aspect may, even in astate in which a collision load has been input during a side collisionof the vehicle, maintain the coupled state between the roofreinforcement portion and the roof side rails, and may enable thecollision load to be stably absorbed.

The vehicle roof structure according to the fourth aspect may increasethe deformation amount of the weak section, and may raise the absorptionefficiency of collision load in a side collision of the vehicle.

The vehicle roof structure according to the fifth aspect may simplifythe configuration of the coupling section while securing the absorptionefficiency of collision load in a side collision of the vehicle.

The vehicle roof structure according to the sixth aspect may suppressthe transmission of collision load in a side collision of the vehicle tothe roof reinforcement portion at an initial stage of the sidecollision.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will be described in detail based on the followingfigures, wherein:

FIG. 1 is an enlarged cross-sectional view (an enlargement of theportion encircled by the double-dotted dashed line in FIG. 5)illustrating configuration of a vehicle roof structure according to afirst exemplary embodiment;

FIG. 2 is a cross-sectional view (a cross-section corresponding to FIG.5) illustrating a vehicle roof structure according to the firstexemplary embodiment in a state during a side collision of the vehicle,as viewed along a vehicle front-rear direction;

FIG. 3A is a cross-sectional view (a cross-section illustrating a statesectioned along line 3A-3A in FIG. 5) of a connection portion between afirst coupling member and a second coupling member of a vehicle roofstructure according to the first exemplary embodiment, as viewed along avehicle width direction;

FIG. 3B is a cross-sectional view (a cross-section illustrating a statesectioned along line 3B-3B in FIG. 5) of a connection portion between asecond coupling member and a roof reinforcement portion of a vehicleroof structure according to the first exemplary embodiment, as viewedalong a vehicle width direction;

FIG. 4 is a plan view (viewed along the direction of arrow 4 in FIG. 5)illustrating configuration of a vehicle roof structure according to thefirst exemplary embodiment;

FIG. 5 is a cross-sectional view (a cross-section illustrating a statesectioned along line 5-5 in FIG. 4) illustrating configuration of avehicle roof structure according to the first exemplary embodiment;

FIG. 6A is a cross-sectional view illustrating a vehicle roof structureaccording to a second exemplary embodiment in a state prior to a sidecollision of the vehicle, as viewed along a vehicle front-reardirection;

FIG. 6B is a cross-sectional view illustrating a vehicle roof structureaccording to the second exemplary embodiment in a state during a sidecollision of the vehicle, as viewed along a vehicle front-reardirection;

FIG. 7A is a cross-sectional view illustrating a vehicle roof structureaccording to a third exemplary embodiment in a state prior to a sidecollision of the vehicle, as viewed along a vehicle front-reardirection; and

FIG. 7B is a cross-sectional view illustrating a vehicle roof structureaccording to the third exemplary embodiment in a state during a sidecollision of the vehicle, as viewed along a vehicle front-reardirection.

DETAILED DESCRIPTION First Exemplary Embodiment

Explanation follows regarding a first exemplary embodiment of a vehicleroof structure according to the present disclosure, with reference toFIG. 1 to FIG. 5. Note that in each of the drawings, the arrow FRindicates the vehicle front side, the arrow UP indicates the vehicleupper side, and the arrow RH indicates the vehicle width direction rightside, as appropriate.

First, explanation is given regarding the schematic configuration of aportion mainly at a vehicle upper side of a vehicle body 12 of a vehicle10 to which the vehicle roof structure according to the presentexemplary embodiment has been applied, with reference to FIG. 5. Notethat, in the present exemplary embodiment, the vehicle body 12 isbasically configured with left-right symmetry, and so explanation willfocus on the configuration of a portion on the vehicle width directionright side of the vehicle body 12.

In sequence from a vehicle front side, a left and right pair of frontpillars (non-illustrated in the drawings), a left and right pair ofcenter pillars 14, and a left and right pair of rear pillars aredisposed at vehicle width direction outer sides of the vehicle body 12.A left and right pair of roof side rails 18 that configure part of aroof section 16 of the vehicle body 12 are supported by respective upperend portions of the front pillars, the center pillars 14, and the rearpillars.

Each roof side rail 18 extends along the vehicle front-rear direction,and is configured including an outer panel 20 that configures a portionon the vehicle width direction outer side of the roof side rail 18, andan inner panel 22 that configures a portion on a vehicle width directioninner side of the roof side rail 18. The outer panel 20 and the innerpanel 22 of each roof side rail 18 are joined together at a join portion24 using spot welding or the like so as to configure a closedcross-section structure, the profile of which has a closedcross-section, as viewed along the vehicle front-rear direction.

The outer panel 20 is provided with a flange portion 20B that extendsout toward the vehicle width direction inner side from a main bodyportion 20A configuring the closed cross-section. The inner panel 22 isprovided with a flange portion 22B that extends out toward the vehiclewidth direction inner side from a main body portion 22A configuring theclosed cross-section. The flange portion 20B and the flange portion 22Bare joined together at the join portion 24 so as to provide each roofside rail 18 with an extension portion 18B that extends out toward thevehicle width direction inner side from a closed cross-sectionconfiguration portion 18A. Note that a roof panel (non-illustrated inthe drawings) that configures the roof side panel roof side rail 18 andthe roof section 16 is disposed at the vehicle upper side of the roofside rail 18.

A roof reinforcement portion 26 that has an angular tube shape extendingin the vehicle width direction and that reinforces the roof section 16is disposed between the roof side rails 18. The roof reinforcementportion 26 is formed of CFRP. As illustrated in FIG. 3B, the roofreinforcement portion 26 has a rectangular shape in which thecross-section profile, as viewed along the length direction of a mainbody portion 26A of the roof reinforcement portion 26 (the vehicle widthdirection), is divided into two in the width direction of the roofreinforcement portion 26 (the vehicle front-rear direction). The roofreinforcement portion 26 is coupled to each roof side rail 18 through afirst coupling member 30 and a second coupling member 32. The firstcoupling member 30 and the second coupling member 32 serve as a couplingsection and are disposed in this sequence from the vehicle widthdirection outer side. Note that, the main body portion 26A andattachment pieces 26B that extend out along the vehicle front-reardirection from a vehicle upper side of the main body portion 26A, arefastened to the second coupling member 32 by fastening members such asrivets 28, as described below, to fix the roof reinforcement portion 26.

The first coupling member 30 is formed of steel, and as illustrated inFIG. 3A, FIG. 3B, and FIG. 4, is disposed with its length direction inthe vehicle width direction, and overall is formed in a hat shape inwhich the cross-section profile, as viewed along the vehicle widthdirection (its length direction), is open toward the vehicle upper side.Specifically, the first coupling member 30 is configured including alower wall portion 30A that configures a vehicle lower side of the firstcoupling member 30, a pair of side wall portions 30B that configure bothvehicle front-rear direction sides of the first coupling member 30, anda pair of extending walls 30C that extend out from the side wallportions 30B.

The lower wall portion 30A has a plate shape with its thicknessdirection in the vehicle vertical direction, and a bulge portion 30Dthat extends along the vehicle width direction and bulges toward thevehicle upper side is formed at a vehicle front-rear direction centralportion of the lower wall portion 30A. The side wall portions 30B areformed in plate shapes that respectively extend out toward the vehicleupper side from peripheral edge portions of the lower wall portion 30Athat extend along the vehicle width direction, and that have theirthickness direction in the vehicle front-rear direction. The extendingwalls 30C are formed in plate shapes that respectively extend out fromperipheral edge portions on the vehicle upper side of the respectiveside wall portions 30B toward opposite sides to that of the bulgeportion 30D, and that have their thickness direction in the vehiclevertical direction.

A portion on the vehicle width direction outer side of the firstcoupling member 30 configures an outer side connection portion 30Econnected to the roof side rail 18. At the outer side connection portion30E, the vehicle vertical direction height of the side wall portions 30Bnarrows on progression toward the vehicle width direction outer side. Aportion of each of the extending walls 30C configuring the outer sideconnection portion 30E is joined to the roof side rail 18 at joiningportions 34 using spot welding or the like to fix the first couplingmember 30. Note that, as also illustrated in FIG. 5, the outer sideconnection portion 30E is joined to the roof side rail 18 at a vehiclelower side portion of the inner panel 22 of the roof side rail 18, andmore specifically, at a portion further toward the vehicle lower sidethan a center of a cross-section of the roof side rail 18 taken alongthe vehicle vertical direction at a location where the joining portions34 are provided to the roof side rail 18.

As illustrated in FIG. 3A, FIG. 3B, and FIG. 4, the second couplingmember 32 is basically configured the same as the first coupling member30. The second coupling member 32 is configured including a lower wallportion 32A, side wall portions 32B, and extending walls 32C. As alsoillustrated in FIG. 5, a portion to the vehicle width direction outerside of a length direction central portion of the second coupling member32 (referred to below as outer side portion 32D) overlaps with a vehicleupper side of the first coupling member 30 and is joined to the firstcoupling member 30 using spot welding or the like at plural joiningportions 36 provided along the length direction of the second couplingmember 32. Note that a bulge portion 32E corresponding to the bulgeportion 30D of the first coupling member 30 is formed at the outer sideportion 32D of the second coupling member 32.

The roof reinforcement portion 26 is disposed at the upper side of aportion to the vehicle width direction inner side of a length directioncentral portion of the second coupling member 32 (referred to below asan inner side portion 32F), in a state overlapping therewith. Pluralpenetrating portions 38 are formed in the inner side portion 32F of thesecond coupling member 32 along the length direction thereof, andpenetrating portions 40 corresponding to the penetrating portions 38 areformed in the roof reinforcement portion 26. In a state in which thepenetrating portions 38 and the penetrating portions 40 are aligned inposition, the penetrating portions 38, 40 are fastened together byrivets 28 to attach the roof reinforcement portion 26 to the secondcoupling member 32. Namely, the inner side portion 32F functions as aninner side connection portion that couples the second coupling member 32and the roof reinforcement portion 26 together.

In the present exemplary embodiment, as illustrated in FIG. 1 and FIG.4, a weak section 42 is set in the first coupling member 30. A featureof the present exemplary embodiment is that a bead portion 44 serving asa protruding bead portion and a bead portion 46 serving as an indentedbead portion are formed at the weak section 42. In the following,detailed explanation will be given regarding configuration of the weaksection 42, and in particular, regarding the bead portions 44, 46, whichconfigure relevant portions of the present exemplary embodiment,

The bead portion 44 is formed spanning across each of the lower wallportion 30A, the side wall portions 30B, and the extending walls 30C ofthe first coupling member 30, and is divided in two at the bulge portion30D formed in the lower wall portion 30A. The bead portion 44 isdisposed so as to run along a peripheral edge portion at the vehiclewidth direction outer side of the second coupling member 32. In otherwords, the bead portion 44 is formed so as to extend along the vehiclefront-rear direction.

The bead portion 44 is bulged so as to form a protrusion on a neutralaxis L side of vehicle vertical direction bending of the first couplingmember 30 due to a collision load F from the vehicle width directionouter side. In other words, the bead portion 44 is formed so as to forma protrusion that protrudes toward the center of a cross-section of thefirst coupling member 30, as viewed along the vehicle width direction,the center being in both the vehicle front-rear direction and thevehicle vertical direction.

Thus, as a result of forming the bead portion 44, at the location wherethe bead portion 44 is provided to the first coupling member 30, thesecond moment of area of the cross-section of the first coupling member30 with respect to a neutral axis L can be made smaller than at otherlocations of the first coupling member 30. The rigidity of the roofreinforcement portion 26 with respect to bending in the vehicle verticaldirection is also set so as to be larger than the rigidity with respectto bending at locations of the first coupling member 30 where the beadportion 44 is formed.

Similarly to the bead portion 44, the bead portion 46 is formed spanningacross each of the lower wall portion 30A, the side wall portions 30B,and the extending walls 30C of the first coupling member 30, and isdivided in two at the bulge portion 30D formed in the lower wall portion30A. The bead portion 46 is disposed so as to run along a peripheraledge portion, or overlap with the peripheral edge portion, at thevehicle width direction inner side of the extension portion 18B of theroof side rail 18, as viewed from the vehicle upper side. In otherwords, the bead portion 46 is formed so as to extend along the vehiclefront-rear direction.

Further, the bead portion 46 is bulged so as to form a protrusion on anopposite side to the neutral axis L of the first coupling member 30 dueto a collision load F. The bead portion 46 can thus be understood asbeing formed so as to protrude toward an opposite side to the vehiclefront-rear direction and vehicle vertical direction center of across-section of the first coupling member 30, as viewed along thevehicle width direction. The bead portion 46 can also be understood asbeing formed indented to an opposite side to the neutral axis L. Thus,by forming the bead portion 46, at the location where the bead portion46 is provided to the first coupling member 30, the second moment ofarea of the cross-section of the first coupling member 30 with respectto the neutral axis L can be made greater than at other locations of thefirst coupling member 30. By providing the bead portions 44, 46 asdescribed above, in a case in which a collision load F is input, aportion of the first coupling member 30 around the bead portions 44, 46deforms before the roof reinforcement portion 26 undergoes bendingdeformation. In the present exemplary embodiment, this portion is setwith the weak section 42.

Note that the bead portions 44, 46 are positioned further toward thevehicle lower side than an apex (a vehicle upper side end portion) ofthe roof side rail 18. A distance S between an apex of the bead portions44 and an apex of the 46 is also set as the same dimension, or slightlylonger than, a distance T between the apex of the bead portion 46 and aleading end of the extension portion 18B of the roof side rail 18. Asalso illustrated in FIG. 2, at a portion between the roof reinforcementportion 26 and the weak section 42 where the first coupling member 30and the second coupling member 32 overlap in the vehicle verticaldirection, rigidity with respect to bending in the vehicle verticaldirection is set to be larger than the rigidity of the roofreinforcement portion 26. Namely, in the present exemplary embodiment,the portion where the first coupling member 30 and the second couplingmember 32 overlap in the vehicle vertical direction functions as a highrigidity portion 48.

Explanation follows regarding the function of the present exemplaryembodiment.

In the present exemplary embodiment, as illustrated in FIG. 5, the leftand right pair of roof side rails 18 that configure part of the roofsection 16 of the vehicle body 12 and that extend along the vehiclefront-rear direction are supported by the center pillars 14 configuringpart of the vehicle body 12. The roof reinforcement portion 26 extendingin the vehicle width direction is disposed between the roof side rails18. In a side collision of the vehicle 10, a collision load Ftransmitted through the center pillars 14 and the roof side rails 18 canbe sustained by the roof reinforcement portion 26. The roofreinforcement portion 26 is also formed of CFRP. Accordingly, thepresent exemplary embodiment may enable a weight reduction in the roofsection 16, and hence in the vehicle body 12.

However, in a case in which the roof reinforcement portion 26 describedabove is formed of CFRP, and in a case in which a collision load F in aside collision of the vehicle 10 were transmitted to the roofreinforcement portion 26 without being absorbed by portions other thanthe roof reinforcement portion 26, the roof reinforcement portion 26 maybreak at an initial stage of the side collision.

The first coupling member 30 and the second coupling member 32 formed ofmetal are included in the present exemplary embodiment, and the roofside rails 18 and the roof reinforcement portion 26 are coupled togetherby the first coupling member 30 and the second coupling member 32. Thefirst coupling member 30 is also provided with the weak section 42. Asillustrated in FIG. 2, the weak section 42 deforms under a collisionload F in the vehicle width direction prior to the roof reinforcementportion 26 undergoing bending deformation under the collision load F.Accordingly, collision load F in a side collision of the vehicle 10 isabsorbed by the weak section 42 at an initial stage of the sidecollision, after which the collision load F is transmitted to the roofreinforcement portion 26 and absorbed by the roof reinforcement portion26. Thus, the present exemplary embodiment may reduce weight of thevehicle body 12 and may secure the absorption efficiency of a collisionload F in a side collision of the vehicle 10.

Moreover, in the present exemplary embodiment, the weak section 42provided to the first coupling member 30 is formed with the bead portion44 that extends along the vehicle front-rear direction and thatprotrudes toward the neutral axis L side of vehicle vertical directionbending of the first coupling member 30 under a collision load F in thevehicle width direction. Accordingly, at the location where the beadportion 44 is provided to the weak section 42, the second moment of areaof the cross-section of the weak section 42 with respect to the neutralaxis L is smaller than at other locations of the weak section 42,enabling the bead portion 44 to be the origin of deformation. Thus, inthe present exemplary embodiment, the origin of deformation in a case inwhich the first coupling member 30 coupling the roof reinforcementportion 26 and the roof side rails 18 together deforms due to acollision load F in a side collision of the vehicle 10, may be set to afreely selected position.

Moreover, in the present exemplary embodiment, the weak section 42 isalso formed with the bead portion 46 that extends along the vehiclefront-rear direction and that is indented to the opposite side to theneutral axis L. The bead portion 46 is positioned further toward thevehicle width direction inner side than the outer side connectionportion 30E connecting the first coupling member 30 and the roof siderails 18.

Thus, in a case in which the first coupling member 30 receives acollision load F in the vehicle width direction, the portion of the weaksection 42 around the bead portion 44 deforms so as to form a protrusiontoward the neutral axis L side, with the bead portion 44 acting as theorigin. In contrast thereto, the location of the weak section 42 wherethe bead portion 46 is provided is less liable to undergo bendingdeformation, since here the second moment of area of the cross-sectionof the weak section 42 with respect to the neutral axis L is greaterthan at other locations of the weak section 42. As a result, as thedeformation process of the weak section 42 progresses, the portionbetween the bead portion 44 and the bead portion 46 deforms so as topivot about the bead portion 46 toward the vehicle vertical direction.

Moreover, the outer side connection portion 30E is provided at a portionto the vehicle lower side of the roof side rails 18, and the beadportions 44, 46 are disposed further toward the vehicle upper side thanthe outer side connection portion 30E and further toward the vehiclelower side than the apex of the roof side rail 18. Accordingly, theportion of the weak section 42 between the bead portion 44 and the beadportion 46 deforms so as to pivot toward the vehicle upper side untilabutted by the extension portion 18B of the roof side rails 18. Afterthe weak section 42 has deformed, the collision load F is transmittedfrom the roof side rail 18 to the roof reinforcement portion 26 throughthe second coupling member 32 and a portion of the first coupling member30 further toward the vehicle width direction inner side than the beadportion 44. As a result, the load placed on the outer side connectionportion 30E due to the collision load F may be suppressed. Thus, in thepresent exemplary embodiment, even in a state in which a collision loadF has been input during a side collision of the vehicle 10, the coupledstate between the roof reinforcement portion 26 and the roof side rails18 is maintained, enabling the collision load F to be stably absorbed.

Furthermore, in the present exemplary embodiment, the high rigidityportion 48 which is set having a higher rigidity with respect to bendingin the vehicle vertical direction than the rigidity of the roofreinforcement portion 26 as a result of the first coupling member 30 andthe second coupling member 32, is provided between the roofreinforcement portion 26 and the weak section 42. Therefore, thecertainty in which the weak section 42 will deform before the roofreinforcement portion 26 due to the bending moment resulting from acollision load F in the vehicle width direction, may be increased. Thus,in the present exemplary embodiment, the transmission of collision loadF in a side collision of the vehicle 10 to the roof reinforcementportion 26 may be suppressed at an initial stage of the side collision.

Second Exemplary Embodiment

Explanation follows regarding a second exemplary embodiment of a vehicleroof structure according to the present disclosure, with reference toFIG. 6A and FIG. 6B. Note that components with the same configuration asin the first exemplary embodiment described above are appended with thesame reference numerals, and explanation thereof is omitted.

As illustrated in FIG. 6A, the vehicle roof structure according to thepresent exemplary embodiment is basically configured the same as that ofthe first exemplary embodiment described above, but differs in theconfiguration of a first coupling member 60. Specifically, although thefirst coupling member 60 is basically configured the same as the firstcoupling member 30, it differs in that it is formed with a bead portion62 serving as a first indented bead portion, a bead portion 64 servingas a second indented bead portion, and a bead portion 66 serving as aprotruding bead portion.

The bead portion 62 is configured similarly to the bead portion 46, andis provided at a location of the first coupling member 60 correspondingto the location where the bead portion 44 is provided to the firstcoupling member 30. The bead portion 64 is also configured similarly tothe bead portion 46, and is provided at a location of the first couplingmember 60 corresponding to the location where the bead portion 46 isprovided to the first coupling member 30. The bead portion 66 isconfigured similarly to the bead portion 44, and is provided between thebead portion 62 and the bead portion 64, specifically, at a locationwhere the distance to the bead portion 62 and the distance to the beadportion 64 are the same distance. Note that in the present exemplaryembodiment, a portion around the bead portions 62, 64, and 66 is set asa weak section 68.

As illustrated in FIG. 6B, with such a configuration, in a case in whichthe first coupling member 60 receives a collision load F in the vehiclewidth direction, the portion of the weak section 68 around the beadportion 66 deforms so as to form a protrusion on the neutral axis Lside, with the bead portion 66 acting as the origin. In contrastthereto, the locations of the weak section 68 where the bead portions62, 64 are provided are less liable to undergo bending deformation,since at these locations, the second moment of area of the cross-sectionof the weak section 68 with respect to the neutral axis L is greaterthan at other locations of the weak section 68. Moreover, the outer sideconnection portion 30E is provided to a portion at the vehicle lowerside of the roof side rails 18, and the bead portions 62, 64, and 66 aredisposed further toward the vehicle upper side than the outer sideconnection portion 30E and further toward the vehicle lower side thanthe apex of the roof side rail 18. Accordingly, as the deformationprocess of the weak section 68 progresses, the portion between the beadportion 62 and the bead portion 64 deforms so as to protrude and kinktoward the vehicle upper side. Thus, in the present exemplaryembodiment, the deformation amount of the weak section 68 is increased,and thus, may improve the absorption efficiency of a collision load F ina side collision of the vehicle 10.

Third Exemplary Embodiment

Explanation follows regarding a third exemplary embodiment of a vehicleroof structure according to the present disclosure, with reference toFIG. 7A and FIG. 7B. Note that components with the same configuration asin the first exemplary embodiment described above are appended with thesame reference numerals, and explanation thereof is omitted.

As illustrated in FIG. 7A, the vehicle roof structure according to thepresent exemplary embodiment is basically configured the same as that ofthe first exemplary embodiment described above, but differs in that thecoupling section is configured by only a coupling member 80.Specifically, the coupling member 80 is configured by a first couplingmember 30 extending directly to the roof reinforcement portion 26, andis configured including an inner side connection portion 80A, an outerside connection portion 80B, and a thinned portion 80C.

The inner side connection portion 80A configures a portion to thevehicle width direction inner side of the coupling member 80, and isfastened to the roof reinforcement portion 26 by a fastening member(non-illustrated in the drawings) such as a rivet. Moreover, the outerside connection portion 80B configures a portion to the vehicle widthdirection outer side of the coupling member 80, and is joined to theroof side rail 18 at a joining portion 82 by spot welding or the like atthe same location as the outer side connection portion 30E. The thinnedportion 80C, which is thinner than the inner side connection portion 80Aand the outer side connection portion 80B and which extends along thevehicle width direction, is formed between the inner side connectionportion 80A and the outer side connection portion 80B. The thinnedportion 80C is a portion that more readily deforms under a collisionload F than the inner side connection portion 80A and the outer sideconnection portion 80B, and in the present exemplary embodiment, thethinned portion 80C functions as a weak section.

As illustrated in FIG. 7B, with the above described configuration, in acase in which a collision load F in the vehicle width direction isinput, the thinned portion 80C undergoes bending deformation, therebyabsorbing the collision load F. This enables the configuration of theweak section to be simplified compared to cases in which a bead portionor the like is provided to the coupling member 80 so as to set the weaksection. Thus, in the present exemplary embodiment, the configuration ofthe coupling member 80 may be simplified while securing the absorptionefficiency of a collision load F in a side collision of the vehicle 10.

Supplemental Explanation of Exemplary Embodiments

(1) Although the first coupling member 30 and the second coupling member32 are provided in the first exemplary embodiment described above,configuration may be made such that the roof reinforcement portion 26and the roof side rails 18 are coupled together by a member that extendsthe first coupling member 30 to the roof reinforcement portion 26. Thisconfiguration may exhibit the same function as the first exemplaryembodiment described above, apart from the function of the high rigidityportion 48.

(2) Although a bead portion, that is bulged so as to form a protrusionon an opposite side to the neutral axis L, is provided in the firstexemplary embodiment and second exemplary embodiment described above,configuration may be made such that only a bead portion that is bulgedso as to form a protrusion on the neutral axis L side is provided. Thisconfiguration may enable the configuration of the first coupling memberto be simplified. Further, elongated hole portions or the like extendingalong the vehicle front-rear direction may be formed so as to functionas the weak section instead of the bead portion.

(3) Although the coupling member that couples the roof reinforcementportion 26 and the roof side rail 18 together has a hat shapedcross-section profile in the exemplary embodiments described above,there is no limitation thereto. For example, depending on theconfiguration of the vehicle 10, the coupling member may take variousconfigurations, such as a flat plate shape.

(4) Further, although the roof reinforcement portion 26 is formed ofCFRP in the exemplary embodiments described above, the roofreinforcement portion 26 may be configured by a fiber reinforced plasticsuch as glass fiber reinforced plastic, so long as it is a materialhaving a specific strength greater than that of iron.

What is claimed is:
 1. A vehicle roof structure comprising: a left andright pair of roof side rails configuring part of a roof section of avehicle body, wherein the roof side rails are supported by a centerpillar configuring part of the vehicle body and extend along a vehiclefront-rear direction; a roof reinforcement portion formed of fiberreinforced plastic, the roof reinforcement portion disposed between theroof side rails so as to extend along a vehicle width direction; and aleft and right pair of coupling sections formed of metal, wherein eachcoupling section couples a corresponding one of the left and right roofside rails and the roof reinforcement portion, and includes a weaksection, wherein the weak section deforms under a collision load in thevehicle width direction prior to the roof reinforcement portionundergoing bending deformation under the collision load, wherein theleft and right pair of roof side rails each include an extension portionthat extends toward the vehicle width direction inner side, and whereinthe weak section is configured to abut the extension portion in a statein which the weak section is deformed due to the collision load, whereinthe weak section is formed with a protruding bead portion, wherein theprotruding bead portion extends along the vehicle front-rear directionand protrudes toward a side of a neutral axis of bending of each of thecoupling sections in a vehicle vertical direction due to the collisionload, wherein the weak section includes: the protruding bead portionformed further toward a vehicle width direction outer side than an innerside connection portion that is a connection portion of each of thecoupling sections and that connects the left or right coupling sectionand the roof reinforcement portion, and an indented bead portionindented to an opposite side of the neutral axis and extending along thevehicle front-rear direction, wherein the indented bead portion isformed further toward a vehicle width direction inner side than an outerside connection portion that is another connection portion of each ofthe coupling sections and that connects the left or right couplingsection and a corresponding one of the left or right roof side rails andfurther toward the vehicle width direction outer side than theprotruding bead portion; and wherein the outer side connection portionis provided at a portion to a vehicle lower side of the roof side rails,and the protruding bead portion and the indented bead portion aredisposed further toward a vehicle upper side than the outer sideconnection portion and further toward the vehicle lower side than anapex of the roof side rails.
 2. The vehicle roof structure of claim 1,further comprising a high rigidity portion provided to each of thecoupling sections and between the roof reinforcement portion and theweak section, the high rigidity portion being set with a higher rigiditywith respect to bending in a vehicle vertical direction than a rigidityof the roof reinforcement portion.
 3. A vehicle roof structurecomprising: a left and right pair of roof side rails configuring part ofa roof section of a vehicle body, wherein the roof side rails aresupported by a center pillar configuring part of the vehicle body andextend along a vehicle front-rear direction; a roof reinforcementportion formed of fiber reinforced plastic, the roof reinforcementportion disposed between the roof side rails so as to extend along avehicle width direction; and a left and right pair of coupling sectionsformed of metal, wherein each coupling section couples a correspondingone of the left and right roof side rails and the roof reinforcementportion, and includes a weak section, wherein the weak section deformsunder a collision load in the vehicle width direction prior to the roofreinforcement portion undergoing bending deformation under the collisionload, wherein the weak section is formed with a protruding bead portion,wherein the protruding bead portion extends along the vehicle front-reardirection and protrudes toward a side of a neutral axis of bending ofeach of the coupling sections in a vehicle vertical direction due to thecollision load, and wherein the weak section includes: a first indentedbead portion indented toward an opposite side to the neutral axis andextending along the vehicle front-rear direction, the first indentedbead portion formed further toward a vehicle width direction outer sidethan an inner side connection portion that is a connection portion ofeach of the coupling sections and that connects the left or rightcoupling section and the roof reinforcement portion, a second indentedbead portion indented to the opposite side of the neutral axis andextending along the vehicle front-rear direction, the second indentedbead portion formed further toward a vehicle width direction inner sidethan an outer side connection portion that is another connection portionof each of the coupling sections and that connects the left or rightcoupling section and a corresponding one of the left or right roof siderails, and the protruding bead portion formed between the first indentedbead portion and the second indented bead portion; and the outer sideconnection portion is provided at a portion at a vehicle lower side ofthe roof side rails, and the protruding bead portion, the first indentedbead portion, and the second indented bead portion are disposed furthertoward a vehicle upper side than the outer side connection portion andfurther toward the vehicle lower side than an apex of the roof siderails.
 4. A vehicle roof structure comprising: a left and right pair ofroof side rails configuring part of a roof section of a vehicle body,wherein the roof side rails are supported by a center pillar configuringpart of the vehicle body and extend along a vehicle front-reardirection; a roof reinforcement portion formed of fiber reinforcedplastic, the roof reinforcement portion disposed between the roof siderails so as to extend along a vehicle width direction; and a left andright pair of coupling sections formed of metal, wherein each couplingsection couples a corresponding one of the left and right roof siderails and the roof reinforcement portion, and includes a weak section,wherein the weak section deforms under a collision load in the vehiclewidth direction prior to the roof reinforcement portion undergoingbending deformation under the collision load, and wherein the weaksection is provided between an inner side connection portion, which is aconnection portion of each of the coupling sections and that connectsthe left or right coupling section and the roof reinforcement portion,and an outer side connection portion, which is another connectionportion of each of the coupling sections and that connects the left orright coupling section and a corresponding one of the left or right roofside rails, and the weak section is configured by a thinned portionformed thinner than the inner side connection portion and the outer sideconnection portion.